Rotary stepping switch



June 1, 1965 w. A. KROPP 3,137,143

- ROTARY STEPPING SWITCH Filed Oct. 25. 1962 INVENTOR Wmus A. KROPP ATTK United States Patent O 3,187,143 RGTARY STEPPING SWITCH Wiliis A. Kropp, Stamford, Conn, assignor to General Time Corporation, New York, N.Y., a corporation of Delaware Filed Oct. 25, 1962, Ser. No. 232,928 4 Claims. or. zoo-res This invention relates generally to switching mechanisms and more particularly concerns rotary stepping switches.

The primary aim of the present invention is to provide a rotary stepping switch which is reliable for long periods of steady use since the switch operators are actuated by rolling action which causes little wear. It is a correlated object to provide a stepping switch drive mechanism with a positive acting lock and interconnected drive which cperates without causing wear due to reverse scuffing of the parts.

It is a further object to provide a rotary stepping switch with positive rolling action wherein the contacts are opened and closed by rapid accelerated and decelerated motion eliminating contact bounce which prevents arcing between the switch contacts. Moreover, it is an object to drive such a switch with positive stepped action after driving inertia has been built up and yet to prevent coasting or over-travel of the switch.

Another object of the invention is to provide a stepping switch of the above type which requires a minimum of driving energy because the switch operators are actuated by rolling action and the actuated operators assist in driving the actuator to the next stepped position. It is an associated object to provide a stepping switch that is locked in all positions enabling it to withstand shock, vibration and rapid acceleration.

It is also an object to provide a rotary stepping switch of the above character which is extremely versatile since a variety of switch operators may be used in many different arranagements and one or multiple actuators may be used.

Moreover, it is an object to provide a rotary stepping switch as described above which is economical to manufacture using mass production techniques and which is longlasting and trouble free in operation due to the simplicity of its design and construction.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIGURE 1 is an exploded schematic view, partially in perspective and partially in enlarged section, of a switching mechanism embodying the present invention;

FIG. 2 is a section taken along the line 2-2 in FIG. 1;

FIG. 3 is a section taken along the line 33 in FIG. 1; and

FIG. 4 is a top view of the contacts as seen from line 4-4 in FIG. 3.

While the invention will be described in connection with a preferred embodiment, it will be understood that I do not intend to limit the invention to that embodiment. On the contrary, I intend to cover all alternatives, modificaions, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Turning now to the drawings, there is shown in FIG. 1 a stepping switch embodying the invention and includ ing a contact actuator device ltla and a ratchet drive assembly 12 which are coupled to a rotary actuator 14 constituting the operator for the switch 10. The ratchet drive assembly includes a frame plate 16 rigidly mounted in a cylindrical housing 18, one end of which is preferably formed to encompass the device 10a and the other end suitably connected to a casing 22 surrounding the rotary 3,l87,l43 Patented June 1, 1965 actuator. In the preferred from, the rotary actuator 14 is an oscillating rotary solenoid having a drive shaft 24 which rotates in the direction of the arrow when the solenoid is energized and which is biased for return movement by a spring 26. It will be understood, however, that other types of rotary actuators may also be employed.

In accordance with the present invention, the contact actuator device 10a is rotatably driven in positive stepped movements by the ratchet drive assembly 12 to sequentially operate a plurality of switch operators disposed adjacent a fixed rack 32 forming a part of the device 16a. In the illustrated embodiment, the switch 10 embodies a plurality of contact sets 30 (FIG. 1) which are supported on the plate 16 by flexible blades 31 and 31a (FIG. 2, 3 and 4) in normally open condition. In this case, the switch operators constitute the blades 31 which, when operated by being flexed toward their respective blades 31a, are effective to close the contacts 39. Preferably, the fixed rack 32 is annular and the contact sets 30' are arranged in a circular pattern about the rack. Any convenient number of contact sets can be provided.

The rack 32 has an enlarged center opening 34 and a piurality of laterally projecting teeth 36 surrounding an output shaft 38 coupled to a ratchet wheel it of the drive assembly 12. The output shaft 38 carries a plurality of rotatable actuators 42 having pinion teeth 44 that mesh with and roll along the rack past the switch blades or operators 31. Preferably, the shaft 38 carries a sleeve element 45 from which a plurality of stub shaft 46 project radially for journalling the autuators 42 so that they eX- tend radially about the periphery of the rack 32 in the plane occupied by the switch operators 31. Thus, it may be seen that as the shaft 38 rotates, the pinion teeth 42 engage the teeth 36 and roll along the rack 32, sequentially operating the operators 31 with a rolling action (see FIGS. 3 and 4) that results in reliable operation with minimum wear.

To drive the switching device 10 in positive stepped movements, the drive assembly 12 includes a pawl lever 50 mounted on the drive shaft 24 of the rotary actuator 14 coaxially with respect to the ratchet wheel 40. A drive pawl 52 is pivotally mounted on one end of the pawl lever and carries a pawl hook 54 biased toward the teeth 56 of the ratchet wheel 40 by a spring 58. Thus, as the pawl lever 56 is oscillated by the rotary actuator between its initial solid line position and final position counterclockwise of the solid line showing, the drive pawl engages and rotates the ratchet wheel 40 and output shaft 38 in stepped sequence.

Pursuant to another feature of the present invention, the drive pawl 52 is forced into ratchet tooth engagement by cam action to minimize the lag due to starting inertia and operate the switching device 10 with positive rolling action. In the preferred embodiment, the drive pawl 52 carries a cam follower 60 which rides in a cam slot 62 cut into the plate 16. The slot 62 defines a lower cam surface 64 having a raised portion or cam lobe 66 that cooperates with the spring 53 to rock the pawl lever 52 and book 54 into engagement with the ratchet wheel 40. As illustrated in FIG. 1, the cam lobe 66 is disposed near the end of the slot 62 adjacent the forward end of the stroke of the drive pawl 52 so that the momentum of the pawl lever 59 imparts substantially instantaneous starting to the ratchet wheel 40 as the pawl book 54 impinges on the ratchet teeth 56.

To prevent overtravel of the ratchet wheel 40 which would cause the actuators 42 to rotate out of center with the rack teeth 36 and thus cause sloppy actuation of the switch operators 31, the cam slot 62 has an enclosed end 68 to stop the cam follower 60. In addition, the lower cam surface 64- is provided with a second sloping cam lobe or rise 76 adjacent the closed end of the slot 62 or which rocks the drive pawl 52 so that the pawl hook 54 bottoms between the teeth 56 of the ratchet wheel as at the end of its stroke. With the hook 54 firmly engaging the teeth 56 of the ratchet wheel, the wheel cannot overtravel and correspondingly the actuators 42 are moved in well defined stepped positions.

Another feature of the invention is to prevent wear of the ratchet teeth 56 due to scuffing of the pawl hook 54 during the back travel of the pawl lever 40. To this end the cam slot 62 is provided with an upper cam surface '71 which rocks the drive pawl 50 counterclockwise, as seen in FIG. 1, against the biasing action of the spring 58 and raises the hook 54 away from the teeth 56. Thus, even with long and repeated operation, neither the ratchet teeth nor the pawl hook wear down which would alter the accuracy and precision of the stepping drive mechanism l2 and cause faulty operation of the stepping switch It).

In order to lock the ratchet wheel 40 and thus the actuators 42 in stepped position incident to the back stroke of the oscillating pawl lever Stl, a locking pawl 72 having a hook '74 on its end is pivotally mounted on the plate 18 and biased into engagement with the ratchet teeth 56 by a spring 76. To insure that the hook '74 remains in engagement with the teeth 56 during the initial portion of the pawl lever stroke, the pawl lever 50 is provided with an extension '78 in which is formed a cam slot 80 to guide a cam follower 82 on the end of the lock pawl 72. The cam slot 80 is shaped to retain the hook 74 in engagement with the teeth 56 until near the end of the stroke of the pawl lever 50, at which time the pawl hook 54 is cammed into engagement with the ratchet teeth 56 and simultaneously the lock pawl 72 is released from engagement with the ratchet wheel 40. For this purpose, the cam slot 80 is provided with a recessed portion M-that allows the follower 82 to drop away from the ratchet wheel 49. Thus, during the terminal portion of the pawl lever stroke, the cam lobe 66 and the relieved portion of the cam slot it cooperate to define the point at which drive of the ratchet wheel begins and, as pointed out above, the second cam rise 70 and. closed end 68 of the slot 62 define the end point of each step of the ratchet wheel 4t).

It is another feature of the invention that the resilient energy stored in the operators 31 when the associated contacts 30 are closed is used to assist in driving the actuators 42 to the next stepped switching position. This is accomplished by disposing the operators 311 between adjacent pairs of the rack teeth 36 (see FlG. 4). Flexing of the operators to close the contacts exerts a reaction force on the actuator teeth 44 that tends to urge the actuators 42 from the rack 32. As soon as the stub shafts 46 move out of alignment with this reaction force, a torque is created tending to roll the actuator on to the next position. This torque assists in overcoming initial inertia of the parts. The positive overtravel prevention resulting from the slope "ill of the cam slot 62 prevents the posssibility of torque developed by deflected operators 31 carrying the actuators beyond the intended end of each step.

In the illustrated embodiment, the rack 32 has been provided with thirty-six teeth as and a set of switch contacts 30 are disposed between each adjacent pair of teeth. If one actuator 42 is mounted on the shaft 38, it will be understood that a single revolution of the shaft will sequentially actuate all thirtysix of the switch operators 3].. If desired, a single switch operator may be disposed between two of the teeth 36 and eighteen actuators 42 placed on the shaft 38 so that a simple on-off switch is provided. Alternatively, if eighteen switch operators 31 are combined with eighteen actuators 42, a multiple switch results which is capable of making and breaking eighteen circuits simultaneously. Various intermediate combinations are, of course possible without departing from the present invention. Moreover, additional switch operators may be ganged with the illustrated operators to simultaneously operate a plurality of circuits at each switch position.

In the preferred embodiment, the ratchet Wheel 40 is also provided with thirty-six teeth 56 corresponding to the thirty-six teeth on the annular rack 32 and the wheel is advanced one tooth per stroke of the pawl lever 50. Thus, it will be appreciated that each stepped movement of the ratchet wheel 40 rotates the actuators 42 so as to center them exactly between the next adjacent teeth 36 on the rack. It will be understood, however, that ratchet wheels and racks having a different number of teeth may be employed. In addition, the stroke of the pawl lever 46 may also be varied so that the ratchet wheel is rotated through an angular distance of more than one tooth per oscillation.

It will now be apparent that the present invention provides a novel stepping switch 10 having great flexibility both in the arrangement and number of switch operators and also the operating sequence in which they are actuated. The positive action of the cam operated drive pawl 52 and the rolling action of the actuators 42 assures rapid as well as precise making and breaking of the switch contacts and thereby avoids arcing. The simplicity and dependability of stepping switches constructed in the above manner also makes them particularly adapted for remotely controlled installations since servicing and wear are minimized. The straightforward layout and arrangement of parts also allows rotary stepping switches of the present invention to be manufactured at low cost, using mass production techniques, without impairing their dependability and precision operating characteristics.

1 claim as my invention:

1. A stepping switch comprising, in combination, a circular fixed rack, a ratchet wheel having an output shaft disposed coaxially with respect to said rack, a pinion coupled to said shaft for bodily movement and meshed with said rack, a pawl lever coaxially mounted with respect to said ratchet wheel and oscillatable between initial and final positions, a drive pawl pivotally mounted on said pawl lever and biased toward said ratchet wheel, a first cam and follower holding said. drive pawl from said ratchet wheel as said pawl lever leaves its initial position and urging said drive pawl against said ratchet wheel as said pawl lever approaches its final position, a lock pawl biased against said ratchet wheel, a second cam and follower connecting said pawl lever and lock pawl preventing said lock pawl from ratcheting over said ratchet wheel until said pawl lever approaches its final position and said drive pawl engages said wheel, means to oscillate said pawl lever between said initial and final positions for angularly stepping said shaft so that said pinion rolls on said rack, and a plurality of switch operators adjacent the path of said pinion for successive actuation thereby so that rolling actuation of said operators takes place.

2. A stepping switch comprising, in combination, a circular fixed rack having teeth, a ratchet wheel having an output shaft disposed coaxially with respect to said rack, a rotatable actuator having pinion teeth meshed with said rack, a pawl lever coaxially mounted with respect to said ratchet'wheel and oscillatable between initial and final positions, a drive pawl pivotally mounted on said pawl lever and biased toward said ratchet wheel, a cam and follower holding said drive pawl from said ratchet wheel as said pawl lever leaves its initial position and urging said drive pawl against said ratchet wheel as said pawl lever approaches its final position, said cam and follower being effective tohold said drive pawl in contact with said ratchet wheel when said pawl lever is in said final position so as to positively prevent overtravel of said ratchet wheel, means to oscillate said pawl lever between said initial and final positions for angularly stepping said shaft so said actuator rolls on said rack, and a plurality of switch operators biased to non-operated positions adjacent said rack and intermediate adjacent teeth so that said operators are actuated when said pinion teeth roll enemas a 1 between said adjacent teeth with the bias on said operators tending to urge said pinion teeth in a direction to rotate said actuator.

3. In a stepping switch, a rotary stepping device, comprising, in combination, a ratchet Wheel having an output shaft, a pawl lever coaxially mounted with respect to said ratchet wheel and oscillatable between initial and final positions, a drive pawl pivotally mounted on said pawl lever and biased toward said ratchet wheel, a first cam and follower holding said drive pawl from said ratchet wheel as said pawl lever leaves its initial position and urging said drive pawl against said ratchet wheel as said pawl lever approaches its final position, a lock pawl biased against said ratchet wheel, a second cam and follower connecting said pawl lever and lock pawl preventing said lock pawl from ratcheting over said ratchet wheel until said pawl lever approaches its final position and said drive pawl engages said wheel, and means to oscillate said pawl lever between said initial and final positions.

4. In a stepping switch, a rotary stepping device comprising, in combination, a ratchet wheel having an output shaft, a pawl lever coaxially mounted with respect to said ratchet wheel and oscillatable between initial and final positions, a drive pawl pivotally mounted on said pawl lever and biased toward said ratchet wheel, a first cam and follower holding said drive pawl from said ratchet wheel as said pawl lever leaves its initial position and urging said drive pawl against said ratchet wheel as said pawl lever approaches its final position, a lock pawl biased against said ratchet wheel, a second earn and follower connecting said pawl lever and lock pawl preventing said lock pawl from ratcheting over said ratchet wheel until said pawl lever approaches its final position and said drive pawl engages said wheel, and means to oscillate said pawl lever between said initial and final positions, said first cam and follower being eifective to hold said drive pawl in contact with said ratchet wheel when said pawl lever is in said final position so as to positively prevent overtravel of said ratchet wheel.

References Cited by the Examiner UNITED STATES PATENTS 10/ 62 Abel 200-153 BERNARD A. GILHEANY, Primary Examiner. 

1. A STEPPING SWITCH COMPRISING, IN COMBINATION, A CIRCULAR FIXED RACK, A RATCHET WHEEL HAVING AN OUTPUT SHAFT DISPOSED COAXIALLY WITH RESPECT TO SAID RACK, A PINION COUPLED TO SAID SHAFT FOR BODILY MOVEMENT AND MESHED WITH SAID RACK, A PAWL LEVER COAXIALLY MOUNTED WITH RESPECT TO SAID RATCHET WHEEL AND OSCILLATABLE BETWEEN INITIAL AND FINAL POSITIONS, A DRIVE PAWL PIVOTALLY MOUNTED ON SAID PAWL LEVER AND BIASED TOWARD SAID RATCHET WHEEL, A FIRST CAM AND FOLLOWER HOLDING SAID DRIVE PAWL FROM SAID RATCHET WHEEL AS SAID PAWL LEVER LEAVES ITS INITIAL POSITION AND URGING SAID DRIVE PAWL AGAINST SAID RATCHET WHEEL AS SAID PAWL LEVER APPROACHES ITS FINAL POSITION, A LOCK PAWL BIASED AGAINST SAID RATCHET WHEEL, A SECOND CAM AND FOLLOWER CONNECTING SAID PAWL LEVER AND LOCK PAWL PREVENTING SAID LOCK PAWL FROM RATCHETING OVER SAID RATCHET WHEEL 